1. Field of the Invention
The present invention concerns a procedure as defined in the preamble to claim 1, and a data traffic system as defined in the preamble to claim 6, for processing data traffic signals carrying information.
2. Description of the Related Art
In prior art a data traffic system is known which comprises data traffic means for forwarding data traffic signals and in which data traffic signals are transmitted between the terminal devices of two subscribers, the A subscriber and the B subscriber. A subscriber is understood to be a customer making use of the services of the data traffic system. The A subscriber is advantageously understood to be that subscriber who initiates the call, or for instance calls the B subscriber he desires, that is advantageously the customer who receives the call. As a rule, the A subscriber is also accountable for the costs accruing during the connection.
In the course of technical development the general level of requirements has gone up. Various. services and characteristics are desired which can be controlled by the user's own tezninal device so that one can call another subscriber in the middle of a call in progress--an intermediate call; connect the call to another number--call transfers pick up an incoming call which is being announced on another terminal device or extension--call pick up; inhibit connection to the own extension of calls coming from certain numbers--call exclusion; and so on. There are several different alternatives. The services and characteristics in particular give added value to the customer-specific services, usually offered to enterprises. In implementing the idea of "The world is my office", these services and characteristics should be connectable to mobile phone systems as well.
At present, the above-mentioned additional functions are implemented in a public exchange which may have several hundred thousand extensions attached. In such implementation intelligent network-based designs are used in aid, which have been described e.g. in the paper "Intelligent Networks: Dedicated to Services, Alcatel Electrical Communication, Vol 65 No 1". With the aid of an intelligent network it is possible, for instance, to assign invoicing for the call to a given credit card number, to direct a customer's call to a non-busy telephone service on the end of a logical chain, such as a medical phone service, which thus may be located in a city or country other than that of is the customer using the service. The task of the intelligent network is to find automatically the first non busy telephone offering the service in question, once the subscriber has with the aid of control commands, such as DTMP commands, given notice that he wants a connection to the service. With the aid of the intelligent network also other similar services can be made available to the subscribers.
The problem in services implemented with the aid of intelligent networks is lack of subscriber specificity. The characteristics of public exchanges implemented with intelligent networks are the same for all subscribers, and the subscribers can use them by issuing control commands prior to establishing the data traffic connection, and while in this service also during the connection. The subscriber cannot himself in the intelligent network in a public exchange program those services and characteristics which he requires. In the present state it is impossible for the subscriber to program in a terminal device operating in a public network such characteristics as he desires, such as dialling and call inhibition, which would be made available from the public exchange. Whenever a subscriber desires subscriber-specific characteristics, he is compelled to procure an exchange of his own, which forwards the calls to the public network and which the subscriber may program as desired. The problem is that a proprietary exchange ties down capital, requires maintenance and space and frequently causes extra inconvenience to the subscriber.